src/graphql/sudoku.ts

@@ -1,5 +1,5 @@
 import { gql } from "../mods.js";
-import { Sudoku, GenerateArguments, SolveArguments } from "../sudoku/index.js";
+import { generate, GenerateArguments } from "../sudoku/index.js";
 
 export const typeDefs = gql`
   """
@@ -22,22 +22,16 @@ export const typeDefs = gql`
   type Query {
     "Generates a new sudoku."
     generate(regionWidth: Int = 3, regionHeight: Int = 3, clues: Int!): Sudoku!
-
-    "Solves the given sudoku."
-    solve(regionWidth: Int = 3, regionHeight: Int = 3, cells: [Int!]!): Sudoku!
   }
 `;
 
-interface SudokuFuncs {
-  solve(args: SolveArguments): Promise<Sudoku> | Sudoku;
-  generate(args: GenerateArguments): Promise<Sudoku> | Sudoku;
-}
-
 export const resolvers = {
   Query: {
-    generate: (obj: any, args: GenerateArguments, ctx: SudokuFuncs) =>
-      ctx.generate(args),
-    solve: (obj: any, args: SolveArguments, ctx: SudokuFuncs) =>
-      ctx.solve(args),
+    generate: (
+      obj: any,
+      { regionWidth, regionHeight, clues }: GenerateArguments
+    ) => {
+      return generate(regionWidth, regionHeight, clues);
+    },
   },
 };

src/main.ts

@@ -1,13 +1,6 @@
 import { Application, bodyParser } from "./mods.js";
 import { applyGraphQL } from "./graphql.js";
 import { typeDefs, resolvers } from "./graphql/index.js";
-import {
-  initializeWorkers,
-  solve,
-  generate,
-  solveSync,
-  generateSync,
-} from "./sudoku/index.js";
 import stoppable from "stoppable";
 
 import cors from "@koa/cors";
@@ -38,25 +31,10 @@ async function main() {
     );
   });
 
-  let sudokuFuncs: any;
-  if (process.env.USE_WORKER_THREADS) {
-    initializeWorkers();
-    sudokuFuncs = {
-      solve,
-      generate,
-    };
-  } else {
-    sudokuFuncs = {
-      solve: solveSync,
-      generate: generateSync,
-    };
-  }
-
   applyGraphQL({
     app,
     typeDefs: typeDefs,
     resolvers: resolvers,
-    context: () => sudokuFuncs,
   });
 
   runtime.server = stoppable(

src/sudoku/dlx.ts

@@ -114,10 +114,10 @@ export class DLX {
 
     let row = c as DNode;
     while ((row = row.down) !== c) {
-      // traverse down the rows this column
+      // traverse DOWN the rows this column contained
       let col = row;
       while ((col = col.right) !== row) {
-        // traverse the columns of this row to the right
+        // traverse the columns of this row (to the RIGHT)
 
         // remove this node from its column, and shrink its column's size
         this.updates++;

src/sudoku/index.ts

@@ -1,9 +1,7 @@
 import { spawn, Thread, Worker } from "threads";
-import type { ModuleThread } from "threads";
-import { SudokuMath } from "./math.js";
-import { prettyPrint } from "./util.js";
 
 import WORKERS from "physical-cpu-count";
+import { prettyPrint } from "./util.js";
 
 const TIMEOUT = 20000;
 
@@ -15,12 +13,6 @@ export type GenerateArguments = {
   clues: number;
 };
 
-export type SolveArguments = {
-  regionWidth: number;
-  regionHeight: number;
-  cells: Cell[];
-};
-
 export type Sudoku = {
   regionWidth: number;
   regionHeight: number;
@@ -28,41 +20,19 @@ export type Sudoku = {
   cells: Cell[];
 };
 
-type SudokuWorker = {
-  generate: (
-    regionWidth: number,
-    regionHeight: number,
-    clues: number
-  ) => Promise<number[]>;
-  solve: (
-    regionWidth: number,
-    regionHeight: number,
-    cells: number[]
-  ) => Promise<[boolean, number[]]>;
-};
-
-const available: ModuleThread<SudokuWorker>[] = [];
-
-function spawnWorker() {
-  spawn<SudokuWorker>(new Worker("./worker")).then((worker) =>
-    available.push(worker)
-  );
+function getWorker() {
+  return spawn(new Worker("./worker"));
 }
 
-export function initializeWorkers() {
+const available: any = [];
+
+function initialize() {
   console.log(`Starting ${WORKERS} worker threads`);
   for (let n = 0; n < WORKERS; n++) {
-    spawnWorker();
+    getWorker().then((worker) => available.push(worker));
   }
 }
-
-function pickWorker() {
-  const proxy = available.pop();
-  if (!proxy) {
-    throw new Error("No workers available right now. Please try again.");
-  }
-  return proxy;
-}
+initialize();
 
 /**
  * Awaits a promise with a timeout.
@@ -82,33 +52,27 @@ function withTimeout<T>(promise: Promise<T>, ms: number, cb: () => any) {
   }).finally(() => clearTimeout(timeout!));
 }
 
-function workerTaskWithTimeout(
-  task: (worker: ModuleThread) => Promise<any>,
-  timeout: number
-) {
-  const worker = pickWorker();
-  let timedOut = false;
-  return withTimeout(task(worker), timeout, () => {
-    timedOut = true;
-    Thread.terminate(worker);
-    spawnWorker();
-    return new Error("Timed out.");
-  }).finally(() => {
-    if (!timedOut) {
-      available.push(worker);
-    }
-  });
+export async function generate(
+  regionWidth: number,
+  regionHeight: number,
+  clues: number
+): Promise<Sudoku> {
+  const proxy = available.pop();
+  if (!proxy) {
+    throw new Error("No workers available right now. Please try again.");
   }
 
-export async function generate({
-  regionWidth,
-  regionHeight,
-  clues,
-}: GenerateArguments): Promise<Sudoku> {
-  const puzzle = await workerTaskWithTimeout(
-    (worker) => worker.generate(regionWidth, regionHeight, clues),
-    TIMEOUT
+  const puzzle = await withTimeout<number[]>(
+    proxy.generate(regionWidth, regionHeight, clues),
+    TIMEOUT,
+    () => {
+      Thread.terminate(proxy);
+      getWorker().then((worker) => available.push(worker));
+      return new Error("Timed out. Try reducing the number of clues.");
+    }
   );
+
+  available.push(proxy);
   prettyPrint(regionWidth, regionHeight, puzzle);
   return {
     regionWidth,
@@ -117,67 +81,3 @@ export async function generate({
     cells: puzzle,
   };
 }
-
-export function generateSync({
-  regionWidth,
-  regionHeight,
-  clues,
-}: GenerateArguments): Sudoku {
-  const math = SudokuMath.get(regionWidth, regionHeight);
-  const cells = math.generate(clues, 1, TIMEOUT);
-  prettyPrint(regionWidth, regionHeight, cells);
-  return {
-    regionWidth,
-    regionHeight,
-    size: (regionWidth * regionHeight) ** 2,
-    cells,
-  };
-}
-
-export async function solve({
-  regionWidth,
-  regionHeight,
-  cells,
-}: SolveArguments): Promise<Sudoku> {
-  const size = (regionWidth * regionHeight) ** 2;
-  if (size !== cells.length) {
-    throw new Error(
-      "The given region dimensions do not align with the number of cells."
-    );
-  }
-  const [solved, result] = await workerTaskWithTimeout(
-    (proxy) => proxy.solve(regionWidth, regionHeight, cells),
-    TIMEOUT
-  );
-  if (!solved) {
-    throw new Error("The given puzzle has no solution.");
-  }
-  return {
-    regionWidth,
-    regionHeight,
-    size,
-    cells: result,
-  };
-}
-
-export function solveSync({
-  regionWidth,
-  regionHeight,
-  cells,
-}: SolveArguments): Sudoku {
-  const size = (regionWidth * regionHeight) ** 2;
-  if (size !== cells.length) {
-    throw new Error(
-      "The given region dimensions do not align with the number of cells."
-    );
-  }
-  if (!SudokuMath.get(regionWidth, regionHeight).solve(cells)) {
-    throw new Error("The given puzzle has no solution.");
-  }
-  return {
-    regionWidth,
-    regionHeight,
-    size,
-    cells,
-  };
-}

src/sudoku/math.ts

@@ -236,11 +236,8 @@ export class SudokuMath {
       }
     };
 
-    let best = 0;
     const attempt = () => {
-      // attempt to remove cells until 'clues' cells remain
-      attempts--;
-      removed.clear();
+      // attempt remove cells until 'clues' cells remain
       shuffle(removeable);
       maskUpto(0);
 
@@ -248,6 +245,7 @@ export class SudokuMath {
         if (elapsed() > totalTime || this.values2 - removed.size == clues) {
           break;
         }
+
         unmaskNextCell();
 
         if (!hasOneSolution()) {
@@ -259,9 +257,6 @@ export class SudokuMath {
 
         removed.add(removeable[i]);
       }
-      if (removed.size > best) {
-        best = removed.size;
-      }
 
       unmaskAll();
     };
@@ -273,37 +268,28 @@ export class SudokuMath {
     ) {
       // try to reach the clue goal up to `attempts` times or as long as
       // elapsed time is less than `totalTime`
+      attempts--;
+      removed.clear();
       attempt();
     }
 
     removed.forEach((index) => {
       completed[index] = 0;
     });
+    console.log("DLX updates:", updates);
     return completed;
   }
 
-  solve(puzzle: Cell[]) {
-    const [header] = this.getDLXHeader(puzzle);
-    let solved = false;
+  solve(existing: Cell[]): void {
+    const [header] = this.getDLXHeader(existing);
     const callback = (solution: DNode[]) => {
       solution.forEach((node) => {
         const meta: NodeMeta = node.meta;
-        puzzle[meta.index] = meta.value;
+        existing[meta.index] = meta.value;
       });
-      solved = true;
       // return the first solution
       return true;
     };
     new DLX(header, callback).search();
-    return solved;
-  }
-
-  static maths: { [key: string]: SudokuMath } = {};
-  static get(regionWidth: number, regionHeight: number) {
-    const key = `${regionWidth}:${regionHeight}`;
-    return (
-      SudokuMath.maths[key] ??
-      (SudokuMath.maths[key] = new SudokuMath(regionWidth, regionHeight))
-    );
   }
 }

src/sudoku/worker.js

@@ -1,12 +1,13 @@
 import { SudokuMath } from "./math.js";
 import { expose } from "threads/worker";
 
+const maths = {};
+
 expose({
   generate(regionWidth, regionHeight, clues) {
-    return SudokuMath.get(regionWidth, regionHeight).generate(clues);
-  },
-  solve(regionWidth, regionHeight, cells) {
-    const result = SudokuMath.get(regionWidth, regionHeight).solve(cells);
-    return [result, cells];
+    const key = `${regionWidth}:${regionHeight}`;
+    const math =
+      maths[key] ?? (maths[key] = new SudokuMath(regionWidth, regionHeight));
+    return math.generate(clues);
   },
 });